Maid 144 enable disabled tests

https://maidsafe.atlassian.net/browse/MAID-144

1, create a new error db_not_presented
    so the situation that bootstrap file not prensented can be detected quicker.
    i.e. not hindered by the SQLite error handling -- re-attempt

2, tune SQLite configuration
    Use WAL, turn off synchronous, use IMMEDIATE